Liquid-chromatographic assay of cefamandole in serum, urine, and dialysis fluid.

We describe a "high-performance" liquid-chromatographic assay for quantifying cefamandole in biological fluids from patients with renal impairment. Serum samples are deproteinized with acetonitrile, then extracted with dichloromethane; dialysis-fluid samples are injected directly; urine samples are diluted appropriately before injection onto the reversed-phase column. The mobile phase is a methanol/aqueous solution (31/69 by vol) containing 500 microL of phosphoric acid, 20 mmol of sodium sulfate, and 200 microL of triethylamine per liter, the mixture being adjusted to pH 6.0 with NaOH. Retention time for cefamandole is 12 min. Its peak is well resolved in highly contaminated samples from renally impaired subjects. The assay's selectivity, reproducibility (within-day and between-day CVs less than 8% in all three sample fluids), and sensitivity--0.5 mg/L in serum, 1.0 mg/L in dialysis fluid, and 5.0 mg/L in urine--make it applicable to pharmacokinetic studies.